This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2001-234048, filed Aug. 1, 2001; No. 2001-234075, filed Aug. 1, 2001; No. 2001-250679, filed Aug. 21, 2001; and No. 2001-272137, filed Sep. 7, 2001, the entire contents of all of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a lightsensitive silver halide emulsion of enhanced photographic speed and a photographic element including the same.
2. Description of the Related Art
Various techniques are being employed for the purpose of improving the light sensitivity of silver halide photographic lightsensitive materials. For example, chemical sensitizers such as sulfur, gold and compounds of Group VIII metals are being employed in order to enhance the inherent photographic speed of silver halides. Spectral sensitization with the use of cyanines and other polymethine dyes is also a technology known in the art to which the present invention pertains.
The phenomenon that, when a spectral sensitizing dye is added to an emulsion in an amount exceeding the optimum amount thereof, the photographic speed of the emulsion is extremely reduced is known as a dye desensitization. As means for improving this phenomenon, there is known a technology comprising utilizing the supersensitization effect by the use of a supersensitizer. This supersensitizer is a generally colorless organic compound which itself does not exert any spectral sensitizing effect, but acts on a sensitizing dye (or excited sensitizing dye) to thereby exert an effect of inhibiting the dye desensitization.
Examples of supersensitizer compounds are listed in, for example, patents such as U.S. Pat. Nos. 2,937,089, 3,706,567, 2,875,058, 3,695,888, 3,457,078, 3,458,318, 3,615,632, 5,192,654, 5,306,612, 2,419,975, 5,459,052 and 4,971,890, and E.P. 554856.
Further, various electron-donating compounds are used in combination with the sensitizing dye in order to enhance the spectral sensitivity of silver halide photographic lightsensitive materials. Examples of electron-donating compounds are listed in U.S. Pat. Nos. 3,695,588 and 3,809,561, and GB""s 255084 and 1064193.
Still further, use is made of compounds comprising such an electron-donating compound linked by a covalent bond with a sensitizing dye. Examples of these compounds are listed in U.S. Pat. Nos. 5,436,121 and 5,478,719 (compounds having an electron-donating styryl base bonded to a monomethine dye) and U.S. Pat. No. 4,607,006 (compounds having an electron-donating group derived from phenothiazine, phenoxazine, carbazole, dibenzophenothiazine, ferrocene or tris-2,2xe2x80x2-bipyridylruthenium, or having a triarylamine skeleton bonded to a silver halide adsorptive group).
However, an ideally enhanced photographic speed has not yet been realized despite implementation of the above various means proposed. In particular, the current situation is that there are few compounds which can attain an enhancement of photographic speed while coping with a problem of fog occurring in accordance with the enhancement of photographic speed or a problem of storage fogging experienced when silver halide photographic lightsensitive materials are stored under severe conditions, for example, high temperature and high humidity, or exposure to hazardous gas evolved at the time of combustion, such as automobile exhaust gas.
Recently, a technology of sensitizing with the use of a compound capable of being fragmented (bond cleavage) after a one-electron oxidation and further releasing another electron as a xe2x80x9ctwo-electron sensitizerxe2x80x9d has been reported in U.S. Pat. Nos. 5,747,235 and 5,747,236, E.P.""s 786692A1, 893731A1 and 893732A1, WO 99/05570, and paper published in Journal of American Chemical Society (xe2x80x9cTwo-Electron Sensitization: A New Concept for Silver Halide Photographyxe2x80x9d, J. Am. Chem. Soc., 122, 11934-11943 (2000)). This compound is described in patent specifications as being characterized in that it is oxidized by a dye hole (sensitizing dye molecule having lost one electron after injection of an electron into a conductive band of silver halide from an excited sensitizing dye) or a hole generated by excitation of silver halides, undergoes a fragmentation reaction and releases another electron to thereby induce an enhancement of photographic speed.
However, even the use of this compound has been unable to attain an ideal technology of enhancing photographic speed whereby a lightsensitive material of high speed/fog ratio and of excellent storability can be produced.
The object of the present invention is to provide a silver halide photographic lightsensitive material which ensures enhanced photographic speed of a photographic emulsion and suppresses fog that is likely to occur in accordance with the enhancement of photographic speed, and which realizes a reduced fog increase even if stored under severe conditions, for example, high temperature and high humidity, or exposure to hazardous gas evolved at the time of combustion, such as automobile exhaust gas.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
The above object has been attained by the following constructions 1 to 10. Particularly, the use of the following novel type of electron-releasing compound has enabled attaining a silver halide emulsion and a silver halide photographic lightsensitive material which realize a high speed/fog ratio and excellent storability.
Construction 1: A silver halide emulsion comprising at least one compound selected from the following four types of electron-releasing compounds, namely:
(Type 1) an electron-releasing compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, the one-electron oxidation product capable of releasing further two or more electrons accompanying a subsequent bond cleavage reaction;
(Type 2) an electron-releasing compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, the one-electron oxidation product capable of releasing further one electron accompanying a subsequent bond cleavage reaction, and the one-electron oxidation product having, in its molecule, two or more adsorptive groups acting on silver halides;
(Type 3) an electron-releasing compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, the one-electron oxidation product capable of releasing further one or more electrons after going through a subsequent bond forming process; and
(Type 4) an electron-releasing compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, the one-electron oxidation product capable of releasing further one or more electrons after going through a subsequent intramolecular ring cleavage reaction.
Construction 2: The silver halide emulsion according to construction 1, wherein the above at least one compound is a compound which undergoes a one-electron oxidation induced by exposure of the silver halide emulsion to light.
Construction 3: The silver halide emulsion according to construction 1 or 2, wherein the above at least one compound is represented by any of the following general formulae (A), (B), (C), (D), (E), (F), (1), (2) and (3): 
In the general formula (A), RED11, represents a one-electron oxidizable reducing group; L11 represents a split-off group; R112 represents a hydrogen atom or substituent; and R111 represents a nonmetallic atomic group capable of forming a cyclic structure corresponding to a tetrahydro form, hexahydro form or octahydro form of a 5-membered or 6-membered aromatic ring (including an aromatic heterocycle) together with carbon atom (C) and RED11.
In the general formula (B), RED12 and L12 have the same meanings as those of RED11 and L11 of the general formula (A), respectively; each of R121 and R122 represents a hydrogen atom or substituent; and ED12 represents an electron-donating group. In the general formula (B), R121 and RED12, or R121 and R122, or ED12 and RED12 may be bonded with each other to thereby form a cyclic structure.
In the general formula (C), RED2 has the same meaning as that of RED12 of the general formula (B); L2 represents a split-off group; each of R21 and R22 represents a hydrogen atom or substituent; and RED2 and R21 may be bonded with each other to thereby form a cyclic structure. The compound represented by the general formula (C) is a compound having, in its molecule, two or more adsorptive groups acting on silver halides.
In the general formula (D), RED3 has the same meaning as that of RED12 of the general formula (B); Y3 represents a reactive group capable of reacting with a one-electron oxidation product formed as a result of a one-electron oxidation of RED3 to thereby form a new bond; and L3 represents a linking group which links between RED3 and Y3.
In the general formulae (E) and (F), each of RED41 and RED42 has the same meaning as that of RED12 of the general formula (B); and each of R40 to R44 and R45 to R49 represents a hydrogen atom or substituent. In the general formula (F), Z42 represents xe2x80x94CR420R421xe2x80x94, xe2x80x94NR423xe2x80x94 or xe2x80x94Oxe2x80x94. Herein, each of R420 and R421 represents a hydrogen atom or substituent; and R423 represents a hydrogen atom, alkyl group, aryl group or heterocyclic group.
In the general formula (1), Z1 represents an atomic group capable of forming a 6-membered ring together with the nitrogen atom and the two carbon atoms of the benzene ring; each of R1, R2 and RN1 represents a hydrogen atom or substituent; X1 represents a group capable of substituting on the benzene ring; m1 is an integer of 0 to 3; and L1 represents a split-off group. In the general formula (2), ED21 represents an electron-donating group; each of R11, R12, RN21, R13 and R14 represents a hydrogen atom or substituent; X21 represents a substituent; m21 is an integer of 0 to 3; and L21 represents a split-off group. Any two of RN21, R13, R14, X21 and ED21 may be bonded with each other to thereby form a cyclic structure. In the general formula (3), each of R31, R32, R33, RN31, Ra and Rb represents a hydrogen atom or substituent; and L31 represents a split-off group. Provided that, when RN31 represents a group other than an aryl group, Ra and Rb are bonded to each other to thereby form an aromatic ring.
Construction 4: The silver halide emulsion according to any of constructions 1 to 3, wherein the electron-releasing compounds of types 1, 3 and 4 are compounds each having in its molecule at least one adsorptive group acting on silver halides or at least one partial structure of a spectral sensitizing dye.
Construction 5: The silver halide emulsion according to any of constructions 1 to 4, wherein each of the above compounds is a compound having in its molecule two or more mercapto groups as a partial structure thereof.
Construction 6: The silver halide emulsion according to any one of constructions 1 to 5, wherein the above compounds have a nitrogen-containing heterocyclic group that is substituted with two or more mercapto groups, as the adsorptive group.
Construction 7: The silver halide emulsion according to any one of constructions 3 to 6, wherein the split-off group of each of the general formulas (A) to (F) and (1) to (3) is a carboxyl group or salt thereof, or hydrogen atom.
Construction 8: The silver halide emulsion according to any of constructions 3 to 7, wherein the compound of general formula (D) is represented by any of the following general formulae (D-1) to (D-4): 
In the general formulae (D-1) to (D-4), each of A100, A200, A300 and A400 represents an aryl group or a heterocyclic group, provided that each of A100, A200 and A400 represents a divalent group resulting from removal of one hydrogen atom from an aryl group or a heterocyclic group. Each of L301, L302, L303 and L304 represents a linking group; and each of Y100, Y200, Y300 and Y400 represents a reactive group. Each of R3100, R3110, R3200, R3210 and R3310 represents a hydrogen atom or substituent. R3110 and A100, or R3210 and A200, or R3310 and A300 may be bonded with each other to thereby form a cyclic structure. X400 represents a hydroxyl group, mercapto group or alkylthio group.
Construction 9: The silver halide emulsion according to any one of constructions 1 to 8, wherein an oxidation potential with respect to the first electron is 0 V or more and 1.4 V or less.
Construction 10: The silver halide emulsion according to any one of constructions 1 to 9, wherein the one-electron oxidation product that is produced after the one-electron oxidation of the compounds of Types 1 to 4 has an oxidation potential of xe2x88x920.7 V or less.
Construction 11: The silver halide emulsion according to any one of constructions 1 to 10, wherein silver halide grains contained in the silver halide emulsion comprise tabular grains having an aspect ratio of 5 or more.
Construction 12: A silver halide emulsion having been chemically sensitized by at least one compound selected from the following four types of electron-releasing compounds, namely:
(Type 1) an electron-releasing compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, the one-electron oxidation product capable of releasing further two or more electrons accompanying a subsequent bond cleavage reaction;
(Type 2) an electron-releasing compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, the one-electron oxidation product capable of releasing further one electron accompanying a subsequent bond cleavage reaction, and the one-electron oxidation product having, in its molecule, two or more adsorptive groups acting on silver halides;
(Type 3) an electron-releasing compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, the one-electron oxidation product capable of releasing further one or more electrons after going through a subsequent bond forming process; and
(Type 4) an electron-releasing compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, the one-electron oxidation product capable of releasing further one or more electrons after going through a subsequent intramolecular ring cleavage reaction.
Construction 13: A silver halide photographic lightsensitive material comprising the silver halide emulsion according to any of constructions 1 to 12.
Construction 14: A silver halide photographic lightsensitive material comprising the silver halide emulsion according to construction 12.
Construction 15: The silver halide photographic lightsensitive material according to construction 13 further comprising at least one reducing compound.
Construction 16: The silver halide photographic lightsensitive material according to construction 14 further comprising at least one reducing compound.
The electron-releasing compound, which is a compound having chemical sensitization capability, for use in the present invention is selected from the following four types of electron-releasing compounds, namely:
(Type 1) an electron-releasing compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, the one-electron oxidation product capable of releasing further two or more electrons accompanying a subsequent bond cleavage reaction;
(Type 2) an electron-releasing compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, the one-electron oxidation product capable of releasing further one electron accompanying a subsequent bond cleavage reaction, and the one-electron oxidation product having, in its molecule, two or more adsorptive groups acting on silver halides;
(Type 3) an electron-releasing compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, the one-electron oxidation product capable of releasing further one or more electrons after going through a subsequent bond forming process; and
(Type 4) an electron-releasing compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product thereof, the one-electron oxidation product capable of releasing further one or more electrons after going through a subsequent intramolecular ring cleavage reaction.
xe2x80x9cCompounds having adsorptive groups acting on silver halides in molecules thereofxe2x80x9d and xe2x80x9ccompounds having partial structures of spectral sensitizing dye in molecules thereofxe2x80x9d are preferred among the above electron-releasing compounds of types 1 to 4. xe2x80x9cCompounds having adsorptive groups acting on silver halides in molecules thereofxe2x80x9d are more preferred.
The electron-releasing compound of Type 1 will be described in detail below.
With respect to the electron-releasing compound of Type 1, the expression xe2x80x9cbond cleavage reactionxe2x80x9d refers to the cleavage of bond between elements, in particular, carbon-carbon bond, carbon-silicon bond, carbon-hydrogen bond, carbon-boron bond, carbon-tin bond or carbon-germanium bond. Further, the cleavage of carbon-hydrogen bond may accompany the above bond cleavage. The electron-releasing compound of Type 1 is a compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product. The one-electron oxidation product only thereafter capable of undergoing a bond cleavage reaction to thereby further release two or more electrons (preferably three or more electrons). In another expression, the electron-releasing compound of Type 1 is a further two or more electrons (preferably three or more electrons) oxidizable compound.
As mentioned in the above description of the related art, compounds each capable of being fragmented (bond cleavage) after a one-electron oxidation and further releasing another electron as a xe2x80x9ctwo-electron sensitizerxe2x80x9d have been described in U.S. Pat. Nos. 5,747,235 and 5,747,236, E.P.""s 786692A1, 893731A1 and 893732A1, WO 99/05570, and paper published in Journal of American Chemical Society (xe2x80x9cTwo-Electron Sensitization: A New Concept for Silver Halide Photographyxe2x80x9d, J. Am. Chem. Soc., 122, 11934-11943 (2000)). Although these compounds are relatively similar to the compound of the present invention in the structure and function, the electron-releasing compound of Type 1 according to the present invention is clearly different from the xe2x80x9ctwo-electron sensitizerxe2x80x9d of the prior art in the number of electrons released after the one-electron oxidation. The most conspicuous characteristic of the compound of the present invention resides in this very respect. That is, the inventors have independently accomplished a novel finding that the compound of the present invention can exert a peculiar unexpected striking sensitizing effect because the number of electrons released after the one-electron oxidation is not one but two or more (preferably three or more).
Compounds preferred among the electron-releasing compounds of Type 1 are represented by the general formula (A), general formula (B), general formula (1), general formula (2) or general formula (3). 
In the general formula (A), RED11 represents a one-electron oxidizable reducing group, and L11 represents a split-off group. R112 represents a hydrogen atom or substituent. R111 represents a nonmetallic atomic group capable of forming a specific 5-membered or 6-membered cyclic structure together with the carbon atom (C) and RED11. Herein, the expression xe2x80x9cspecific 5-membered or 6-membered cyclic structurexe2x80x9d means a cyclic structure corresponding to a tetrahydro form, hexahydro form or octahydro form of 5-membered or 6-membered aromatic ring (including an aromatic heterocycle).
In the general formula (B), RED12 represents a one-electron oxidizable reducing group, and L12 represents a split-off group. Each of R121 and R122 represents a hydrogen atom or substituent. ED12 represents an electron-donating group. In the general formula (B), R121 and RED12; R121 and R122; ED12 and RED12 may be bonded with each other to thereby form a cyclic structure.
These compounds are compounds which, after a one-electron oxidation of the reducing group represented by RED11 or RED12 of the general formula (A) or general formula (B), can spontaneously split L11 or L12 through a bond cleavage reaction, namely, cleave the C (carbon atom)xe2x80x94L11 bond or the C (carbon atom)xe2x80x94L12 bond to thereby further release two or more, preferably three or more, electrons. 
In the general formula (1), Z1 represents an atomic group capable of forming a 6-membered ring together with the nitrogen atom and two carbon atoms of the benzene ring; each of R1, R2 and RN1 represents a hydrogen atom or substituent; X1 represents a group capable of substituting on the benzene ring; m1 is an integer of 0 to 3; and L1 represents a split-off group. In the general formula (2), ED21 represents an electron-donating group; each of R11, R12, RN21, R13 and R14 represents a hydrogen atom or substituent; X21 represents a substituent; m21 is an integer of 0 to 3; and L21 represents a split-off group. Any two of RN21, R13, R14, X21 and ED21 may be bonded with each other to thereby form a cyclic structure. In the general formula (3), each of R31, R32, R33, RN31, Ra and Rb represents a hydrogen atom or substituent; and L31 represents a split-off group. Provided that, when RN31 represents a group other than an aryl group, Ra and Rb are bonded to each other to thereby form an aromatic ring.
These compounds are compounds which, after a one-electron oxidation, can spontaneously split L1, L21 or L31 through a bond cleavage reaction, namely, cleave the C (carbon atom)xe2x80x94L1 bond, the C (carbon atom)xe2x80x94L21 bond or the C (carbon atom)xe2x80x94L31 bond to thereby further release two or more, preferably three or more, electrons.
The compounds of the general formula (A) will first be described in detail below.
In the general formula (A), the one-electron oxidizable reducing group represented by RED11 is a group capable of bonding with R111 described later to thereby effect a specific cyclization. The one-electron oxidizable reducing group can be, for example, a divalent group corresponding to a monovalent group, as mentioned below, having one hydrogen atom removed therefrom at a position which is appropriate for cyclization. The monovalent group can be, for example, any of an alkylamino group, arylamino group (e.g., anilino, naphthylamino), heterocyclic amino group (e.g., benzothiazolylamino, pyrrolylamino), alkylthio group, arylthio group (e.g., phenylthio), heterocyclic thio group, alkoxy group, aryloxy group (e.g., phenoxy), heterocyclic oxy group, aryl group (e.g., phenyl, naphthyl, anthranyl) and aromatic or nonaromatic heterocyclic group (5 to 7-membered monocyclic or condensed-ring heterocycle containing at least one heteroatom selected from a nitrogen atom, a sulfur atom, an oxygen atom and a selenium atom, which heterocycle can be, for example, a tetrahydroquinoline ring, tetrahydroisoquinoline ring, tetrahydroquinoxaline ring, tetrahydroquinazoline ring, indoline ring, indole ring, indazole ring, carbazole ring, phenoxazine ring, phenothiazine ring, benzothiazoline ring, pyrrole ring, imidazole ring, thiazoline ring, piperidine ring, pyrrolidine ring, morpholine ring, benzimidazole ring, benzimidazoline ring, benzoxazoline ring or methylenedioxyphenyl ring) (hereinafter, for simplicity, RED11 is referred to as denoting a monovalent group). These groups may each have a substituent.
The substituent can be, for example, any of a halogen atom, alkyl groups (including, e.g., an aralkyl group, cycloalkyl group, active methine group), an alkenyl group, alkynyl group, aryl group, heterocyclic group (preferably, 5- to 7-membered ring having at least one hetero atom selected from N, O and s, with its substitution position is not questioned), heterocyclic group containing a quaternated nitrogen atom (e.g., pyridinio, imidazolio, quinolinio or isoquinolinio), acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, carboxyl group or salt thereof, sulfonylcarbamoyl group, acylcarbamoyl group, sulfamoylcarbamoyl group, carbazoyl group, oxalyl group, oxamoyl group, cyano group, carbonimidoyl group, thiocarbamoyl group, hydroxyl group, alkoxy groups (including a group containing ethyleneoxy or propyleneoxy repeating units), aryloxy group, heterocyclic oxy group, acyloxy group, alkoxy- or aryloxy-carbonyloxy group, carbamoyloxy group, sulfonyloxy group, amino group, alkyl-, aryl- or heterocyclic-amino group, acylamino group, sulfonamido group, ureido group, thioureido group, imido group, alkoxy- or aryloxy-carbonylamino group, sulfamoylamino group, semicarbazido group, thiosemicarbazido group, hydrazino group, ammonio group, oxamoylamino group, alkyl- or aryl-sulfonylureido group, acylureido group, acylsulfamoylamino group, nitro group, mercapto group, alkyl-, aryl- or heterocyclic-thio group, alkyl- or aryl-sulfonyl group, alkyl- or aryl-sulfinyl group, sulfo group or salt thereof, sulfamoyl group, acylsulfamoyl group, sulfonylsulfamoyl group or salt thereof, and group containing a phosphoramide or phosphoric ester structure. These substituents may be further substituted with these substituents.
In the general formula (A), L11 represents a split-off group which can be split off through a bond cleavage only after a one-electron oxidation of the reducing group represented by RED11. L11 represents, for example, a carboxyl group or salt thereof, silyl group, hydrogen atom, triarylboron anion, trialkylstannyl group, trialkylgermyl group, or a group of the formula xe2x80x94CRC1RC2RC3.
When L11 represents a salt of carboxyl group, as a counter ion for forming a salt, there can be mentioned, for example, an alkali metal ion (e.g., Li+, Na+, K+ or Cs+), an alkaline earth metal ion (e.g., Mg2+, Ca2+ or Ba2+), a heavy metal ion (e.g., Ag+ or Fe2+/3+), an ammonium ion or a phosphonium ion. When L11 represents a silyl group, the silyl group is, for example, a trialkylsilyl group, an aryldialkylsilyl group or a triarylsilyl group. The alkyl of these groups can be, for example, methyl, ethyl, benzyl or t-butyl. The aryl of these groups can be, for example, phenyl.
When L11 represents a triarylboron anion, the aryl thereof is preferably a substituted or unsubstituted phenyl, wherein the substituent can be any of those which may be had by RED11.
When L11 represents a trialkylstannyl group or a trialkylgermyl group, the alkyl thereof is a substituted or unsubstituted linear, branched or cyclic alkyl having 1 to 24 carbon atoms, wherein the substituent can be any of those which may be had by RED11.
When L11 represents a group of the formula xe2x80x94CRC1RC2RC3, each of RC1, RC2 and RC3 independently represents any of a hydrogen atom, alkyl group, aryl group, heterocyclic group, alkylthio group, arylthio group, alkylamino group, arylamino group, heterocyclic amino group, alkoxy group, aryloxy group and hydroxyl group. These may be bonded with each other to thereby form a cyclic structure. Each of these may further have a substituent. The substituent can be any of those which may be had by RED11. Provided however that, when one of RC1, RC2 and RC3 represents a hydrogen atom or alkyl group, the remaining two do not represent a hydrogen atom or alkyl group. It is preferred that each of RC1, RC2 and RC3 independently represent an alkyl group, aryl group (especially, phenyl), alkylthio group, arylthio group, alkylamino group, arylamino group, heterocyclic group, alkoxy group or hydroxyl group. Specific examples thereof include phenyl, p-dimethylaminophenyl, p-methoxyphenyl, 2,4-dimethoxyphenyl, p-hydroxyphenyl, methylthio, phenylthio, phenoxy, methoxy, ethoxy, dimethylamino, N-methylanilino, diphenylamino, morpholino, thiomorpholino and hydroxyl. Examples of groups having a cyclic structure formed by mutual bonding of these include 1,3-dithiolan-2-yl, 1,3-dithian-2-yl, N-methyl-1,3-thiazolidin-2-yl and N-benzylbenzothiazolidin-2-yl.
Preferred groups of the formula xe2x80x94CRC1RC2RC3 can be, for example, trityl, tri(p-hydroxyphenyl)methyl, 1,1-diphenyl-1-(p-dimethylaminophenyl)methyl, 1,1-diphenyl-1-(methylthio)methyl, 1-phenyl-1,1-(dimethylthio)methyl, 1,3-dithiolan-2-yl, 2-phenyl-1,3-dithiolan-2-yl, 1,3-dithian-2-yl, 2-phenyl-1,3-dithian-2-yl, 2-methyl-1,3-dithian-2-yl, N-methyl-1,3-thiazolidin-2-yl, 2-methyl-3-methyl-1,3-thiazolidin-2-yl, N-benzylbenzothiazolidin-2-yl, 1,1-diphenyl-1-dimethylaminomethyl and 1,1-diphenyl-1-morpholinomethyl group. It is also preferred that the group of the formula xe2x80x94CRC1RC2RC3 be the same group as the residue resulting from removal of L11 from the general formula (A) as a consequence of selection within the above scopes with respect of the RC1, RC2 and RC3.
In the general formula (A), R112 represents a hydrogen atom or substituent capable of substituting on the carbon atom. When R112 represents a substituent capable of substituting on the carbon atom, the substituent can be, for example, any of those mentioned as substituent examples with respect to the RED11 having a substituent. Provided however that R112 and L11 do not represent the same group.
In the general formula (A), R111 represents a nonmetallic atomic group capable of forming a specific 5-membered or 6-membered cyclic structure together with the carbon atom (C) and RED11. Herein, the expression xe2x80x9cspecific 5-membered or 6-membered cyclic structurexe2x80x9d formed by R111 means a cyclic structure corresponding to a tetrahydro form, hexahydro form or octahydro form of 5-membered or 6-membered aromatic ring, including an aromatic heterocycle. Herein, the terminology xe2x80x9chydro formxe2x80x9d means a cyclic structure resulting from partial hydrogenation of internal carbon to carbon double bonds or carbon to nitrogen double bonds of an aromatic ring, including an aromatic heterocycle. The tetrahydro form refers to a structure resulting from hydrogenation of two carbon to carbon double bonds or carbon to nitrogen double bonds. The hexahydro form refers to a structure resulting from hydrogenation of three carbon to carbon double bonds or carbon to nitrogen double bonds. The octahydro form refers to a structure resulting from hydrogenation of four carbon to carbon double bonds or carbon to nitrogen double bonds. As a result of hydrogenation, the aromatic ring becomes a partially hydrogenated nonaromatic cyclic structure.
Specifically, as examples of 5-membered monocycles, there can be mentioned a pyrrolidine ring, imidazolidine ring, thiazolidine ring, pyrazolidine ring and oxazolidine ring which correspond to tetrahydro forms of aromatic rings including a pyrrole ring, imidazole ring, thiazole ring, pyrazole ring and oxazole ring, respectively. As examples of 6-membered monocycles, there can be mentioned tetrahydro or hexahydro forms of aromatic rings such as a pyridine ring, pyridazine ring, pyrimidine ring and pyrazine ring. Particular examples thereof include a piperidine ring, tetrahydropyridine ring, tetrahydropyrimidine ring and piperazine ring. As examples of 6-membered condensed rings, there can be mentioned a tetralin ring, tetrahydroquinoline ring, tetrahydroisoquinoline ring, tetrahydroquinazoline ring and tetrahydroquinoxaline ring which correspond to tetrahydro forms of aromatic rings including a naphthalene ring, quinoline ring, isoquinoline ring, quinazoline ring and quinoxaline ring, respectively. As examples of tricyclic compounds, there can be mentioned a tetrahydrocarbazole ring, which is a tetrahydro form of a carbazole ring, and an octahydrophenanthridine ring, which is an octahydro form of a phenanthridine ring.
These cyclic structures may further be substituted. As examples of suitable substituents, there can be mentioned those described above with respect to substituents which may be had by the RED11. Substituents of these cyclic structures may be further bonded with each other to thereby form a ring. The thus newly formed ring is a nonaromatic carbon ring or heterocycle.
Preferred range of compounds represented by the general formula (A) of the present invention will be described below.
In the general formula (A), L11 preferably represents a carboxyl group or salt thereof, or hydrogen atom. More preferably, L11 is a carboxyl group or salt thereof. As a counter ion of the salt, there can preferably be mentioned an alkali metal ion or an ammonium ion. An alkali metal ion (especially Li+, Na+ or K+ ion) is most preferred.
When L11 represents a hydrogen atom, it is preferred that the compound represented by the general formula (A) have an intramolecular base moiety. By virtue of the action of the base moiety, the compound represented by the general formula (A) is oxidized, and thereafter the hydrogen atom represented by L11 is deprotonized to thereby enable further release of an electron therefrom.
Herein, the base refers to, for example, a conjugated base of acid exhibiting a pKa value of about 1 to about 10. As the base, there can be mentioned, for example, any of nitrogen-containing heterocycles (pyridines, imidazoles, benzimidazoles, thiazoles, etc.), anilines, trialkylamines, an amino group, carbon acids (active methylene anion, etc.), a thioacetate anion, carboxylate (xe2x80x94COOxe2x88x92), sulfate (xe2x80x94SO3xe2x88x92) and an amine oxide ( greater than N+(Oxe2x88x92)xe2x80x94). Preferred base is a conjugated base of acid exhibiting a pKa value of about 1 to about 8. Carboxylate, sulfate and an amine oxide are more preferred. Carboxylate is most preferred. When these bases have an anion, a counter cation may be had thereby. The counter cation can be, for example, an alkali metal ion, an alkaline earth metal ion, a heavy metal ion, an ammonium ion or a phosphonium ion.
These bases are linked at an arbitrary position thereof to the compound represented by the general formula (A). The position at which the base moiety is bonded may be any of RED11, R111 and R112 of the general formula (A). Also, the bases may be linked at substituents of these groups.
When L11 represents a hydrogen atom, it is preferred that the hydrogen atom and the base moiety be linked to each other through an atomic group consisting of 8 or less atoms. More preferably, the linkage is made by an atomic group consisting of 5 to 8 atoms. Herein, what is counted as a linking atomic group refers to an atomic group which links the hydrogen atom to the central atom of base moiety (namely, an atom having an anion, or an atom having a lone electron pair) by a covalent bond. For example, with respect to carboxylate, two atoms of xe2x80x94Cxe2x80x94Oxe2x88x92 are counted. With respect to sulfate, two atoms of Sxe2x80x94Oxe2x88x92 are counted. Also, the carbon atom represented by C in the general formula (A) is included in the count.
In the general formula (A), when L11 represents a hydrogen atom and when RED11 represents an aniline whose nitrogen atom forms a 6-membered monocyclic saturated ring structure (for example, a piperidine ring, piperazine ring, morpholine ring, thiomorpholine ring or selenomorpholine ring) together with R111, it is preferred that the compound have an adsorptive group acting on silver halides in its molecule. It is more preferred that the compound simultaneously have an intramolecular base moiety, the base moiety and the hydrogen atom linked to each other through an atomic group consisting of 8 or less atoms.
In the general formula (A), it is preferred that RED11 represents an alkylamino group, arylamino group, heterocyclic amino group, aryl group, or aromatic or nonaromatic heterocyclic group. As the heterocyclic group, preferred use is made of, for example, tetrahydroquinolinyl, tetrahydroquinoxalinyl, tetrahydroquinazolinyl, indolyl, indolenyl, carbazolyl, phenoxazinyl, phenothiazinyl, benzothiazolinyl, pyrrolyl, imidazolyl, thiazolidinyl, benzimidazolyl, benzimidazolinyl or 3,4-methylenedioxyphenyl-1-yl. More preferred use is made of an aryl group (especially a phenyl group) or arylamino group (especially an anilino group) having 18 or less carbon atoms. When RED11 represents an aryl group, it is preferred that the aryl group has at least one electron-donating group (the number of electron-donating groups is preferably 4 or less, more preferably 1 to 3). Herein, the electron-donating group specifically refers to a hydroxyl group, alkoxy group, mercapto group, sulfonamido group, acylamino group, alkylamino group, arylamino group, heterocyclic amino group, active methine group, electron-excess aromatic heterocyclic group (e.g., indolyl, pyrrolyl, imidazolyl, benzimidazolyl, thiazolyl, benzthiazolyl or indazolyl), or a nonaromatic nitrogen-containing heterocyclic group that is bonded to the carbon atom of the general formula (A) via its nitrogen atom (e.g., pyrrolidinyl, indolinyl, piperidinyl, piperazinyl or morpholino). Herein, the active methine group refers to a methine group substituted with two electron-withdrawing groups. Herein, the electron-withdrawing groups refer to an acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, alkylsulfonyl group, arylsulfonyl group, sulfamoyl group, trifluoromethyl group, cyano group, nitro group and carbonimidoyl group. These two electron-withdrawing groups may be bonded with each other to thereby form a circular structure. When RED11 represents an aryl group, the substituent of the aryl group is preferably an alkylamino group, hydroxyl group, alkoxy group, mercapto group, sulfonamido group, active methine group, or nonaromatic nitrogen-containing heterocyclic group that is bonded to the carbon atom of the general formula (A) via its nitrogen atom. More preferably, the substituent is an alkylamino group, hydroxyl group, active methine group, or nonaromatic nitrogen-containing heterocyclic group that is bonded to the carbon atom of the general formula (A) via its nitrogen atom. Most preferably, the substituent is an alkylamino group, or nonaromatic nitrogen-containing heterocyclic group that is bonded to the carbon atom of the general formula (A) via its nitrogen atom.
In the general formula (A), R112 preferably represents any of a hydrogen atom, alkyl group, aryl group (e.g., phenyl), alkoxy group (e.g., methoxy, ethoxy or benzyloxy), hydroxyl group, alkylthio group (e.g., methylthio or butylthio), amino group, alkylamino group, arylamino group and heterocyclic amino group, each preferably having 18 or less carbon atoms. More preferably, R112 represents any of a hydrogen atom, alkyl group, alkoxy group, phenyl group, alkylamino group or hydroxyl group, each preferably having 10 or less carbon atoms.
In the general formula (A), R111 preferably represents a nonmetallic atomic group capable of forming the following specific 5-membered or 6-membered cyclic structure together with the carbon atom (C) and RED11. Specifically, the cyclic structure formed by R111 may be, for example, either of a pyrrolidine ring and an imidazolidine ring which correspond to tetrahydro forms of monocyclic 5-membered aromatic rings including a pyrrole ring and imidazole ring, respectively. Also, the cyclic structure may be a tetrahydro or hexahydro form of monocyclic 6-membered aromatic ring such as a pyridine ring, pyridazine ring, pyrimidine ring or pyrazine ring. For example, the cyclic structure may be a piperidine ring, tetrahydropyridine ring, tetrahydropyrimidine ring or piperazine ring. Further, the cyclic structure may be any of a tetralin ring, tetrahydroquinoline ring, tetrahydroisoquinoline ring, tetrahydroquinazoline ring and tetrahydroquinoxaline ring which correspond to tetrahydro forms of condensed-ring of 6-membered aromatic rings including a naphthalene ring, a quinoline ring, isoquinoline ring, quinazoline ring and quinoxaline ring, respectively. Still further, the cyclic structure may be a tetrahydrocarbazole ring which is a tetrahydro form of a tricyclic aromatic carbazole ring, or octahydrophenanthridine ring which is an octahydro form of a phenanthridine ring. The cyclic structure formed by R111 is more preferably selected from a pyrrolidine ring, imidazolidine ring, piperidine ring, tetrahydropyridine ring, tetrahydropyrimidine ring, piperazine ring, tetrahydroquinoline ring, tetrahydroquinazoline ring, tetrahydroquinoxaline ring and tetrahydrocarbazole ring. Most preferably, the cyclic structure formed by R111 is selected from a pyrrolidine ring, piperidine ring, piperazine ring, tetrahydroquinoline ring, tetrahydroquinazoline ring, tetrahydroquinoxaline ring and tetrahydrocarbazole ring. Optimally, the cyclic structure formed by R111 is selected from a pyrrolidine ring, piperidine ring and tetrahydroquinoline ring.
Now, the general formula (B) will be described in detail.
With respect to the RED12 and L12 of the general formula (B), not only the meanings but also the preferred ranges thereof are the same as those of the RED11 and L11 of the general formula (A), respectively. Provided however that RED12 represents a monovalent group unless the following cyclic structure is formed thereby. For example, the monovalent group can be any of those mentioned with respect to RED11. With respect to R121 and R122, not only the meanings but also the preferred ranges thereof are the same as those of the R112 of the general formula (A). ED12 represents an electron-donating group. R121 and RED12; R121 and R122; or ED12 and RED12 may be bonded with each other to thereby form a cyclic structure.
In the general formula (B), the electron-donating group represented by ED12 refers to a hydroxyl group, alkoxy group, mercapto group, alkylthio group, arylthio group, heterocyclic thio group, sulfonamido group, acylamino group, alkylamino group, arylamino group, heterocyclic amino group, active methine group, electron-excess aromatic heterocyclic group (e.g., indolyl, pyrrolyl or indazolyl), a nonaromatic nitrogen-containing heterocyclic group that is bonded to the carbon atom of the general formula (B) via its nitrogen atom (e.g., pyrrolidinyl, piperidinyl, indolinyl, piperazinyl or morpholino), or an aryl group substituted with any of these electron-donating groups (e.g., p-hydroxyphenyl, p-dialkylaminophenyl, an o,p-dialkoxyphenyl or 4-hydroxynaphthyl). Herein, the active methine group is the same as described above as a substituent when RED11 represents an aryl group. ED12 preferably represents a hydroxyl group, alkoxy group, mercapto group, sulfonamido group, alkylamino group, arylamino group, active methine group, electron-excess aromatic heterocyclic group, nonaromatic nitrogen-containing heterocyclic group that is bonded to the carbon atom of the general formula (B) via its nitrogen atom, or phenyl group substituted with any of these electron-donating groups. More preferably, ED12 represents a hydroxyl group, mercapto group, sulfonamido group, alkylamino group, arylamino group, active methine group, nonaromatic nitrogen-containing heterocyclic group that is bonded to the carbon atom of the general formula (B) via its nitrogen atom, or phenyl group substituted with any of these electron-donating groups (e.g., p-hydroxyphenyl, p-dialkylaminophenyl or o,p-dialkoxyphenyl).
In the general formula (B), R121 and RED12; R122 and R121; or ED12 and RED12 may be bonded with each other to thereby form a cyclic structure. The thus formed cyclic structure is a substituted or unsubstituted cyclic structure consisting of a 5 to 7-membered monocyclic or condensed-ring nonaromatic carbon ring or heterocycle. When R121 and RED12 form a cyclic structure, the thus formed cyclic structure can be, for example, a pyrrolidine ring, pyrroline ring, imidazolidine ring, imidazoline ring, thiazolidine ring, thiazoline ring, pyrazolidine ring, pyrazoline ring, oxazolidine ring, oxazoline ring, indane ring, piperidine ring, piperazine ring, morpholine ring, tetrahydropyridine ring, tetrahydropyrimidine ring, indoline ring, tetralin ring, tetrahydroquinoline ring, tetrahydroisoquinoline ring, tetrahydroquinoxaline ring, tetrahydro-1,4-oxazine ring, 2,3-dihydrobenzo-1,4-oxazine ring, tetrahydro-1,4-thiazine ring, 2,3-dihydrobenzo-1,4-thiazine ring, 2,3-dihydrobenzofuran ring or 2,3-dihydrobenzothiophene ring. When ED12 and RED12 form a cyclic structure, ED12 preferably represents an amino group, alkylamino group or arylamino group. The cyclic structure formed thereby can be, for example, a tetrahydropyrazine ring, piperazine ring, tetrahydroquinoxaline ring or tetrahydroisoquinoline ring. When R122 and R121 form a cyclic structure, the thus formed cyclic structure can be, for example, a cyclohexane ring or cyclopentane ring.
Those which are more preferred among the compounds of the general formula (A) of the present invention are represented by the following general formulae (10) to (12). Those which are more preferred among the compounds of the general formula (B) are represented by the following general formulae (13) and (14). 
With respect to the L100, L101, L102, L103 and L104 of the general formulae (10) to (14), not only the meanings but also the preferred ranges thereof are the same as those of the L11 of the general formula (A). With respect to R1100 and R1101; R1110 and R1111; R1120 and R1121; R1130 and R1131; and R1140 and R1141; not only the meanings but also the preferred ranges thereof are the same as those of the R122 and R121, respectively of the general formula (B). With respect to the ED13 and ED14, not only the meanings but also the preferred ranges thereof are the same as those of the ED12 of the general formula (B). Each of X10, X11, X12, X13 and X14 represents a substituent capable of substituting on the benzene ring. Each of m10, m11, m12, m13 and m14 is an integer of 0 to 3. When it is 2 or more, a plurality of X10, X11, X12, X13 or X14 groups may be the same or different. Each of Y12 and Y14 represents an amino group, alkylamino group, arylamino group, nonaromatic nitrogen-containing heterocyclic group that is bonded to the benzene ring of the general formula (12) or (14) via its nitrogen atom (e.g., pyrrolyl, piperidinyl, indolinyl, piperazino or morpholino), hydroxyl group or alkoxy group.
Each of Z10, Z11 and Z12 represents a nonmetallic atomic group capable of forming a specific cyclic structure. The specific cyclic structure formed by Z10 means a cyclic structure corresponding to a tetrahydro form or hexahydro form of 5- or 6-membered, monocyclic or condensed-ring, nitrogen-containing aromatic heterocycle. As such a cyclic structure, there can be mentioned, for example, a pyrrolidine ring, imidazolidine ring, thiazolidine ring, pyrazolidine ring, piperidine ring, tetrahydropyridine ring, tetrahydropyrimidine ring, piperazine ring, tetrahydroquinoline ring, tetrahydroisoquinoline ring, tetrahydroquinazoline ring or tetrahydroquinoxaline ring. The specific cyclic structure formed by Z11 refers to a tetrahydroquinoline ring or tetrahydroquinoxaline ring. The specific cyclic structure formed by Z12 refers to a tetralin ring, tetrahydroquinoline ring or tetrahydroisoquinoline ring.
Each of RN11 and RN13 represents a hydrogen atom or substituent capable of substituting on the nitrogen atom. The substituent can be, for example, any of an alkyl group, alkenyl group, alkynyl group, aryl group, heterocyclic group and acyl group, preferably an alkyl group or aryl group, each of which preferably have 18 or less carbon atoms, more preferably 10 or less carbon atoms.
The substituents capable of substituting on the benzene ring, represented by X10, X11, X12, X13 or X14, can be, for example, those which may be had by the RED11 of the general formula (A). Preferably, the substituents can be a halogen atom, alkyl group, aryl group, heterocyclic group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, cyano group, alkoxy group (including a group containing ethyleneoxy or propyleneoxy repeating units), alkyl-, aryl- or heterocyclic-amino group, an acylamino group, sulfonamido group, ureido group, thioureido group, imido group, alkoxy- or aryloxy-carbonylamino group, nitro group, alkyl-, aryl- or heterocyclic-thio group, alkyl- or aryl-sulfonyl group, a sulfamoyl group, etc. Each of m10, m11, m12, m13 and m14 is preferably an integer of 0 to 2, more preferably 0 or 1.
Each of Y12 and Y14 preferably represents an alkylamino group, arylamino group, nonaromatic nitrogen-containing heterocyclic group that is bonded to the benzene ring of the general formula (12) or (14) via its nitrogen atom, hydroxyl group or alkoxy group. More preferably, each of Y12 and Y14 represents an alkylamino group, 5- or 6-membered nonaromatic nitrogen-containing heterocyclic group that is bonded to the benzene ring of the general formula (12) or (14) via its nitrogen atom, or hydroxyl group. Most preferably, each of Y12 and Y14 represents an alkylamino group (especially, a dialkylamino group) or a 5- or 6-membered nonaromatic nitrogen-containing heterocyclic group that is bonded to the benzene ring of the general formula (12) or (14) via its nitrogen atom.
In the general formula (13), R1131 and X13; R1131 and RN13; R1130 and X13; or R1130 and RN13 may be bonded with each other to thereby form a cyclic structure. In the general formula (14), R1141 and X14; or R1141 and R1140; ED14 and X14; or R1140 and X14 may be bonded with each other to thereby form a cyclic structure. The thus formed cyclic structure is a substituted or unsubstituted cyclic structure consisting of a 5- to 7-membered monocyclic or condensed-ring nonaromatic carbon ring or heterocycle. When, in the general formula (13), R1131 and X13 are bonded with each other to thereby form a cyclic structure, or R1131 and RN13 are bonded with each other to thereby form a cyclic structure, the resultant compound, like that wherein no cyclic structure is formed, is a preferred example of the compounds of the general formula (13). As the cyclic structure formed by R1131 and X13 in the general formula (13), there can be mentioned, for example, any of an indoline ring, in which case, R1131 represents a single bond, tetrahydroquinoline ring, tetrahydroquinoxaline ring, 2,3-dihydrobenzo-1,4-oxazine ring and 2,3-dihydrobenzo-1,4-thiazine ring. Of these, an indoline ring, tetrahydroquinoline ring and tetrahydroquinoxaline ring are especially preferred. As the cyclic structure formed by R1131 and RN13 in the general formula (13), there can be mentioned, for example, any of a pyrrolidine ring, pyrroline ring, imidazolidine ring, imidazoline ring, thiazolidine ring, thiazoline ring, pyrazolidine ring, pyrazoline ring, oxazolidine ring, oxazoline ring, piperidine ring, piperazine ring, morpholine ring, tetrahydropyridine ring, tetrahydropyrimidine ring, indoline ring, tetrahydroquinoline ring, tetrahydroisoquinoline ring, tetrahydroquinoxaline ring, tetrahydro-1,4-oxazine ring, 2,3-dihydrobenzo-1,4-oxazine ring, tetrahydro-1,4-thiazine ring, 2,3-dihydrobenzo-1,4-thiazine ring, 2,3-dihydrobenzofuran ring and 2,3-dihydrobenzothiophene ring. Of these, a pyrrolidine ring, piperidine ring, tetrahydroquinoline ring and tetrahydroquinoxaline ring are especially preferred.
When, in the general formula (14), R1141 and X14 are bonded with each other to thereby form a cyclic structure, or ED14 and X14 are bonded with each other to thereby form a cyclic structure, the resultant compound, like that wherein no cyclic structure is formed, is a preferred example of the compounds of the general formula (14). As the cyclic structure formed by the bonding of R1141 and X14 in the general formula (14), there can be mentioned, for example, an indane ring, tetralin ring, tetrahydroquinoline ring, tetrahydroisoquinoline ring or indoline ring. As the cyclic structure formed by the bonding of ED14 and X14, there can be mentioned, for example, a tetrahydroisoquinoline ring or tetrahydrocinnoline ring.
Now, the general formulae (1) to (3) will be described.
In the general formulae (1) to (3), each of R1, R2, R11, R12 and R31 independently represents a hydrogen atom or substituent. With respect to these, not only the meanings but also the preferred ranges thereof are the same as those of the R112 of the general formula (A). Each of L1, L21 and L31 independently represents a split-off group, which can be any of those mentioned as examples in the above description of the L11 of the general formula (A). The preferred ranges thereof are also the same as mentioned there. X1 and X21 represent substituents capable of substituting on the benzene ring. Each thereof independently represents any of those mentioned as substituent examples with respect to substituted RED11 of the general formula (A). Each of m1 and m21 is an integer of 0 to 3, preferably 0 to 2, and more preferably 0 or 1.
Each of RN1, RN21 and RN31 represents a hydrogen atom or substituent capable of substituting on the nitrogen atom. The substituent can preferably be any of an alkyl group, aryl group and heterocyclic group. These groups may further have a substituent. This substituent can be any of those which may be had by the RED11 of the general formula (A). Each of RN1, RN21 and RN31 preferably represents a hydrogen atom, alkyl group or aryl group, more preferably a hydrogen atom or alkyl group.
Each of R13, R14, R32, R33, Ra and Rb independently represents a hydrogen atom or substituent capable of substituting on the carbon atom. The substituent can be any of those which may be had by the RED11 of the general formula (A). The substituent can preferably be, for example, an alkyl group, aryl group, acyl group, alkoxycarbonyl group, carbamoyl group, cyano group, alkoxy group, acylamino group, sulfonamido group, ureido group, thioureido group, alkylthio group, arylthio group, alkylsulfonyl group, arylsulfonyl group or sulfamoyl group.
In the general formula (1), Z1 represents an atomic group capable of forming a 6-membered ring together with two carbon atoms of the benzene ring and the nitrogen atom. The 6-membered ring formed with Z1 is a nonaromatic carbon ring or heterocycle fused with the benzene ring of the general formula (1). For example, it can be any of a tetrahydroquinoline ring, tetrahydroquinoxaline ring and tetrahydroquinazoline ring. These may have a substituent. The substituent can be any of those mentioned as examples when the R112 of the general formula (A) represents a substituent, and the preferred range thereof is also the same as mentioned there.
In the general formula (1), Z1 preferably represents an atomic group capable of forming a tetrahydroquinoline ring or tetrahydroquinoxaline ring together with the two carbon atoms of the benzene ring and the nitrogen atom.
In the general formula (2), ED21 represents an electron-donating group. With respect to the ED21, not only the meaning but also the preferred range thereof is the same as those of the ED12 of the general formula (B).
In the general formula (2), any two of RN21, R13, R14, X21 and ED21 may be bonded with each other to thereby form a cyclic structure. The cyclic structure formed by RN21 and X21 is preferably a 5 to 7-membered nonaromatic carbon ring or heterocycle fused with the benzene ring of the general formula (2). For example, it can be a tetrahydroquinoline ring, tetrahydroquinoxaline ring, indoline ring or 2,3-dihydro-5,6-benzo-1,4-thiazine ring. Preferably, it is a tetrahydroquinoline ring, tetrahydroquinoxaline ring or indoline ring.
In the general formula (3), when RN31 represents a group other than aryl, Ra and Rb are bonded with each other to thereby form an aromatic ring. This aromatic ring is an aryl group (e.g., a phenyl group or naphthyl group) or an aromatic heterocyclic group (e.g., a pyridine ring group, pyrrole ring group, quinoline ring group or indole ring group). An aryl group is preferred. The aromatic ring group may have a substituent. The substituent can be any of those mentioned when X1 of the general formula (1) represents a substituent, and the preferred range thereof is also the same as mentioned there.
In the general formula (3), it is preferred that Ra and Rb be bonded with each other to thereby form an aromatic ring (especially a phenyl group).
In the general formula (3), R32 preferably represents, for example, a hydrogen atom, alkyl group, aryl group, hydroxyl group, alkoxy group, mercapto group or amino group. When R32 represents a hydroxyl group, it is a preferred mode that simultaneously R33 represent an electron-withdrawing group. This electron-withdrawing group refers to any of an acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, alkylsulfonyl group, arylsulfonyl group, sulfamoyl group, trifluoromethyl group, cyano group, nitro group and carbonimidoyl group. Of these, an acyl group, alkoxycarbonyl group, carbamoyl group and cyano group are preferred.
The electron-releasing compound of Type 2 will be described below.
The electron-releasing compound of Type 2 is a compound capable of undergoing a one-electron oxidation to thereby form a one-electron oxidation product and capable of, only thereafter, undergoing a bond cleavage reaction to thereby further release another electron. That is, the electron-releasing compound of Type 2 is a compound capable of undergoing a further one-electron oxidation. The above bond cleavage reaction refers to the cleavage of bond between elements, in particular, carbon-carbon bond, carbon-silicon bond, carbon-hydrogen bond, carbon-boron bond, carbon-tin bond or carbon-germanium bond. Further, the cleavage of carbon-hydrogen bond may accompany the above bond cleavage.
Among the electron-releasing compounds of Type 2, those preferred are represented by the general formula (C). 
The compound of the general formula (C) is a compound wherein, after the one-electron oxidation of the reducing group represented by RED2, L2 is spontaneously split off through a bond cleavage reaction, namely, the C (carbon atom)xe2x80x94L2 bond is cleaved, so that further another electron can be released.
The compound of the general formula (C) is a compound having, in its molecule, two or more (preferably 2 to 6, more preferably 2 to 4) adsorptive groups acting on silver halides. More preferably, the compound of the general formula (C) is a compound having a nitrogen-containing heterocyclic group substituted with two or more mercapto groups as the adsorptive group. The number of adsorptive groups is preferably in the range of 2 to 6, more preferably 2 to 4. The adsorptive groups will be described later.
With respect to RED2 of the general formula (C), not only the meaning but also the preferred range thereof is the same as those of the RED12 of the general formula (B). With respect to L2, not only the meaning but also the preferred range thereof is the same as those of the L11 of the general formula (A). When L2 represents a silyl group, the compound is one having, in its molecule, a nitrogen-containing heterocyclic group substituted with two or more mercapto groups as adsorptive groups. Each of R21 and R22 represents a hydrogen atom or substituent. With respect to these, not only the meanings but also the preferred ranges thereof are the same as those of the R112 of the general formula (A). RED2 and R21 may be bonded with each other to thereby form a cyclic structure.
The thus formed cyclic structure is preferably a 5- to 7-membered monocyclic or condensed-ring nonaromatic carbon ring or heterocycle, which may have a substituent. Provided however that the cyclic structure is not one corresponding to a tetrahydro form, hexahydro form or octahydro form of an aromatic ring or aromatic heterocycle. The substituent can be any of those mentioned as substituent examples with respect to substituted RED11 of the general formula (A). The cyclic structure is preferably one corresponding to a dihydro form of an aromatic ring or aromatic heterocycle, which can be, for example, any of a 2-pyrroline ring, 2-imidazoline ring, 2-thiazoline ring, 1,2-dihydropyridine ring, 1,4-dihydropyridine ring, indoline ring, benzimidazoline ring, benzothiazoline ring, benzoxazoline ring, 2,3-dihydrobenzothiophene ring, 2,3-dihydrobenzofuran ring, benzo-xcex1-pyran ring, 1,2-dihydroquinoline ring, 1,2-dihydroquinazoline ring and 1,2-dihydroquinoxaline ring.
Of these, a 2-imidazoline ring, 2-thiazoline ring, indoline ring, benzimidazoline ring, benzothiazoline ring, benzoxazoline ring, 1,2-dihydropyridine ring, 1,2-dihydroquinoline ring, 1,2-dihydroquinazoline ring and 1,2-dihydroquinoxaline ring are preferred. An indoline ring, benzimidazoline ring, benzothiazoline ring and 1,2-dihydroquinoline ring are more preferred. An indoline ring is most preferred.
The electron-releasing compound of Type 3 will be described below.
The electron-releasing compound of Type 3 is a compound characterized in that it can undergo a one-electron oxidation to thereby form a one-electron oxidation product, the one-electron oxidation product undergoing a subsequent bond forming step to thereby further release one or more electrons. The bond forming step refers to the formation of bond between atoms, in particular, carbon-carbon bond, carbon-nitrogen bond, carbon-sulfur bond or carbon-oxygen bond.
The compound of Type 3 is preferably a compound characterized in that it can undergo a one-electron oxidation to thereby form a one-electron oxidation product, the one-electron oxidation product subsequently reacting with a reactive group moiety (a carbon to carbon double bond moiety, a carbon to carbon triple bond moiety, an aromatic group moiety or a nonaromatic heterocyclic group moiety of benzo condensed rings) which is copresent in the molecule to thereby form a bond, followed by further release of one or more electrons.
The one-electron oxidation product formed by the one-electron oxidation of the electron-releasing compound of Type 3 refers to a cation radical species, which may undergo splitting of a proton to thereby form a neutral radical species. This one-electron oxidation product (cation radical species or neutral radical species) reacts with a carbon to carbon double bond moiety, a carbon to carbon triple bond moiety, an aromatic group moiety and a nonaromatic heterocyclic group moiety of benzo condensed rings which are copresent in the molecule, thereby forming interatomic bonds such as carbon-carbon bond, carbon-nitrogen bond, carbon-sulfur bond and carbon-oxygen bond. Thus, a new intramolecular cyclic structure is formed. Simultaneously or thereafter, further one or more electrons are released. The characteristic of the electron-releasing compound of Type 3 resides in this respect.
More specifically, the compound of Type 3 is characterized in that the bond forming reaction after the one-electron oxidation leads to formation of a new radical species of cyclic structure, from which the second electron is further released directly or through splitting of a proton to thereby cause an oxidation thereof.
Furthermore, the electron-releasing compounds of Type 3 include one exhibiting such a capability that the thus formed two-electron oxidation product subsequently undergoes a tautomeric reaction accompanying a transfer of proton either by way of a hydrolytic reaction or directly to thereby further release one or more, generally two or more, electrons, resulting in an oxidation thereof. Still further, the compounds of Type 3 include one exhibiting such a capability that, without undergoing such a tautomeric reaction, further one or more, generally two or more, electrons are directly released from the two-electron oxidation product, resulting in oxidation thereof.
The compound of Type 3 is preferably represented the general formula (D). 
In the general formula (D), RED3 represents the same meanings as defined for RED12 of the general formula (B).
In the general formula (D), RED3 preferably represents an arylamino group, heterocyclic amino group, aryloxy group, arylthio group, aryl group, or aromatic or nonaromatic heterocyclic group (especially preferably a nitrogen-containing heterocyclic group). More preferably, RED3 represents an arylamino group, heterocyclic amino group, aryl group, or aromatic or nonaromatic heterocyclic group. With respect to the heterocyclic group, it is preferred to use, for example, a tetrahydroquinoline ring group, tetrahydroquinoxaline ring group, tetrahydroquinazoline ring group, indoline ring group, indole ring group, carbazole ring group, phenoxazine ring group, phenothiazine ring group, benzothiazoline ring group, pyrrole ring group, imidazole ring group, thiazole ring group, benzimidazole ring group, benzimidazoline ring group, benzothiazoline ring group or 3,4-methylenedioxyphenyl-1-yl ring group.
An arylamino group (especially anilino), an aryl group (especially phenyl) or an aromatic or nonaromatic heterocyclic group is most preferred as RED3, wherein the number of carbon atoms of the aryl group or heterocyclic group moiety is preferably 18 or less.
When RED3 represents an aryl group, it is preferred that the aryl group has at least one electron-donating group. Herein, the electron-donating group specifically refers to a hydroxyl group, alkoxy group, mercapto group, alkylthio group, sulfonamido group, acylamino group, alkylamino group, arylamino group, heterocyclic amino group, active methine group, electron-excess aromatic heterocyclic group (e.g., indolyl, pyrrolyl or indazolyl), or a nonaromatic nitrogen-containing heterocyclic group that is bonded to L3 via its nitrogen atom (e.g., pyrrolidinyl, indolinyl, piperidinyl, piperazinyl, morpholino or thiomorpholino). Herein, the active methine group refers to a methine group substituted with two electron-withdrawing groups. Herein, the electron-withdrawing groups refer to an acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, alkylsulfonyl group, arylsulfonyl group, sulfamoyl group, trifluoromethyl group, cyano group, nitro group and carbonimidoyl group. These two electron-withdrawing groups may be bonded with each other to thereby form a cyclic structure.
When RED3 represents a substituted aryl group, the substituent of the substituted aryl group is preferably an alkylamino group, hydroxyl group, alkoxy group, mercapto group, sulfonamido group, active methine group, or nonaromatic nitrogen-containing heterocyclic group that is bonded to L3 via its nitrogen atom. More preferably, the substituent is an alkylamino group, hydroxyl group, active methine group, or nonaromatic nitrogen-containing heterocyclic group that is bonded to L3 via its nitrogen atom. Most preferably, the substituent is an alkylamino group, or nonaromatic nitrogen-containing heterocyclic group that is bonded to L3 via its nitrogen atom.
In the general formula (D), Y3 represents a reactive group capable of reacting with a one-electron oxidation product formed as a result of a one-electron oxidation of RED3 to thereby form a new bond. Specifically, Y3 represents an organic group having a carbon to carbon double bond moiety, carbon to carbon triple bond moiety, aromatic group moiety, or benzo-condensed nonaromatic heterocyclic group moiety. When the reactive group represented by Y3 is an organic group having a carbon to carbon double bond or carbon to carbon triple bond moiety, the moiety may have a substituent. Two of such substituents may be bonded with each other thereby to form a ring. As an organic group comprising a carbon to carbon double bond moiety and carbon to carbon triple bond moiety, a substituted or unsubstituted vinyl group and a substituted or unsubstituted ethynyl group can be mentioned, respectively. The substituent of the substituted organic group can preferably be any of, for example, an alkyl group (preferably having 1 to 8 carbon atoms), aryl group (preferably having 6 to 12 carbon atoms), cyano group, alkoxycarbonyl group (preferably having 2 to 8 carbon atoms), carbamoyl group, acyl group and electron-donating group. Herein, the electron-donating group refers to any of an alkoxy group (preferably having 1 to 8 carbon atoms), hydroxyl group, amino group, alkylamino group (preferably having 1 to 8 carbon atoms), arylamino group (preferably having 6 to 12 carbon atoms), heterocyclic amino group (preferably having 2 to 6 carbon atoms), sulfonamido group, acylamino group, active methine group, mercapto group, an alkylthio group (preferably having 1 to 8 carbon atoms), arylthio group (preferably having 6 to 12 carbon atoms) and aryl group having any of these groups as a substituent (the number of carbon atoms of the aryl moiety is preferably in the range of 6 to 12). The hydroxyl group may be protected with a silyl group. For example, a trimethylsilyloxy group, t-butyldimethylsilyloxy group, triphenylsilyloxy group, triethylsilyloxy group or phenyldimethylsilyloxy group can be mentioned as the electron-donating group.
When Y3 represents an organic group comprising a carbon to carbon double bond moiety that has a substituent, the substituent thereof is more preferably, for example, an alkyl group, phenyl group, acyl group, cyano group, alkoxycarbonyl group, carbamoyl group or electron-donating group. Herein, the electron-donating group preferably refers to any of an alkoxy group, hydroxyl group, which may be protected with a silyl group, amino group, alkylamino group, arylamino group, sulfonamido group, active methine group, mercapto group, alkylthio group and phenyl group having any of these electron-donating groups as a substituent, among the substituents mentioned above.
When the carbon to carbon double bond moiety has a hydroxyl group as a substituent, Y3 contains a partial structure of the formula  greater than C1=xe2x95x90C2(xe2x80x94OH)xe2x80x94. This may be tautomerized into a partial structure of the formula  greater than C1Hxe2x80x94C2(xe2x95x90O)xe2x80x94. Further, in this structure, it is preferred that the substituent on C1 carbon be an electron-withdrawing group. In this instance, Y3 has a partial structure of xe2x80x9cactive methylene groupxe2x80x9d or xe2x80x9cactive methine groupxe2x80x9d. The electron-withdrawing groups capable of providing this partial structure of active methylene group or active methine group are the same as mentioned in the above description of xe2x80x9cactive methine groupsxe2x80x9d.
When Y3 represents an organic group having a carbon to carbon triple bond moiety that has a substituent, the substituent is preferably, for example, an alkyl group, phenyl group, alkoxycarbonyl group, carbamoyl group or electron-donating group. Herein, the electron-donating group preferably refers to any of an alkoxy group, amino group, alkylamino group, arylamino group, heterocyclic amino group, sulfonamido group, acylamino group, active methine group, mercapto group, alkylthio group and phenyl group having any of these electron-donating groups as a substituent.
When Y3 represents an organic group having an aromatic group moiety, the aromatic group is preferably an indole ring group or an aryl group (especially preferably a phenyl group) having an electron-donating group as a substituent. Herein, the electron-donating group preferably refers to a hydroxyl group, which may be protected with a silyl group, alkoxy group, amino group, alkylamino group, active methine group, sulfonamido group or mercapto group.
When Y3 represents an organic group having a nonaromatic heterocyclic group of benzo condensed rings, the nonaromatic heterocyclic group of benzo condensed rings is preferably one having an aniline structure as an internal partial structure, which can be, for example, an indoline ring group, 1,2,3,4-tetrahydroquinoline ring group, 1,2,3,4-tetrahydroquinoxaline ring group or 4-quinolone ring group.
In the general formula (D), the reactive group represented by Y3 is more preferably an organic group containing a carbon to carbon double bond moiety, aromatic group moiety or nonaromatic heterocyclic group of benzo condensed rings. Still more preferably, the reactive group is an organic group having a carbon to carbon double bond moiety, phenyl group having an electron-donating group as a substituent, indole ring group, or nonaromatic heterocyclic group of benzo condensed rings having an aniline structure as an internal partial structure. Herein, it is more preferred that the carbon to carbon double bond moiety have at least one electron-donating group as a substituent.
When the reactive group represented by Y3 of the general formula (D) has the same partial structure as that of the reducing group represented by RED3 of the general formula (D) as a result of selection within the range described hereinbefore, also, preferred examples of the compounds of the general formula (D) are provided thereby.
In the general formula (D), L3 represents a linking group which links between RED3 and Y3. For example, L3 represents a group consisting of each of, or each of combinations of, a single bond, alkylene group, arylene group, heterocyclic group, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94NRNxe2x80x94, xe2x80x94C(xe2x95x90O)xe2x80x94, xe2x80x94SO2xe2x80x94, xe2x80x94SOxe2x80x94 and xe2x80x94P(xe2x95x90O)xe2x80x94. Herein, RN represents a hydrogen atom, alkyl group, aryl group or heterocyclic group. The linking group represented by L3 may have a substituent. The substituent can be any of those mentioned hereinbefore as substituents which may be had by RED11 of the general formula (A). The linking group represented by L3 can engage in linkage by replacing one arbitrary hydrogen atom of each of the groups represented by RED3 and L3 at an arbitrary position thereof.
The linking group represented by L3 of the general formula (D) is preferably such that, when the cationic radical species (X+.) formed as a result of oxidation of RED3 of the general formula (D) or radical species (X.) formed through splitting of proton therefrom reacts with the reactive group represented by Y3 of the general formula (D) to thereby form a bond, the relevant atomic groups engaging therein can form a 3- to 7-membered cyclic structure including L3. From this viewpoint, it is preferred that the radical species (X+. or X.), the reactive group represented by Y3 and the group L3 be linked to each other by a group of 3 to 7 atoms.
As a preferred example of L3, there can be mentioned a divalent linking group selected from a single bond, alkylene group (especially methylene, ethylene or propylene), an arylene group (especially phenylene), xe2x80x94C(xe2x95x90O)xe2x80x94 group, xe2x80x94Oxe2x80x94 group, xe2x80x94NHxe2x80x94 group, xe2x80x94N(alkyl group)xe2x80x94 group and combinations thereof.
Among the compounds of the general formula (D), preferred compounds are represented by the following general formulae (D-1) to (D-4): 
In the general formulae (D-1) to (D-4), each of A100, A200 and A400 represents an arylene group or divalent heterocyclic group, and A300 represents an aryl group or a heterocyclic group. The preferred range thereof is the same as that of RED3 of the general formula (D). Each of L301, L302, L303 and L304 represents a linking group. With respect to these, not only the meanings but also the preferred ranges thereof are the same as those of L3 of the general formula (D). Each of Y100, Y200, Y300 and Y400 represents a reactive group. With respect to these, not only the meanings but also the preferred ranges thereof are the same as those of Y3 of the general formula (D). Each of R3100, R3110, R3200, R3210 and R3310 represents a hydrogen atom or substituent. Each of R3100 and R3110 preferably represents a hydrogen atom, alkyl group or aryl group. Each of R3200 and R3310 preferably represents a hydrogen atom. R3210 preferably represents a substituent. This substituent is preferably an alkyl group or aryl group. R3110 and A100; R3210 and A200; R3310 and A300 may be bonded with each other to thereby form a cyclic structure. The thus formed cyclic structure is preferably, for example, a tetralin ring, indane ring, tetrahydroquinoline ring or indoline ring. X400 represents a hydroxyl group, mercapto group or alkylthio group, preferably represents a hydroxyl group or mercapto group, and more preferably represents a mercapto group.
Among the compounds of the general formulae (D-1) to (D-4), the compounds of the general formulae (D-2), (D-3) and (D-4) are preferred. The compounds of the general formulae (D-2) and (D-3) are more preferred.
The electron-releasing compound of Type 4 will be described below.
The electron-releasing compound of Type 4 is a compound having a circular structure substituted with a reducing group, which compound can undergo a one-electron oxidation of the reducing group and thereafter a cleavage reaction of the circular structure to thereby further release one or more electrons.
In the compound of Type 4, the cyclic structure is cleaved after a one-electron oxidation. Herein, the cyclic cleavage reaction refers to the following scheme of reaction: 
In the formulae, the compound (a) represents a compound of Type 4. In the compound (a), D represents a reducing group, and X and Y represent atoms forming a bond of the circular structure which is cleaved after a one-electron oxidation. First, the compound (a) undergoes a one-electron oxidation to thereby form a one-electron oxidation product (b). Then, the Dxe2x80x94X single bond is converted to a double bond, and simultaneously the Xxe2x80x94Y bond is cleaved to thereby form an open-ring product (c). An alternative route wherein a proton is split from the one-electron oxidation product (b) to thereby form a radical intermediate (d), from which an open-ring product (e) is similarly formed, may be taken. One or more electrons are further released from the thus formed open-ring product (c) or (e). The characteristic of this compound of the present invention resides in this respect.
The cyclic structure of the compound of Type 4 refers to a nonaromatic, saturated or unsaturated, monocyclic or condensed-ring, 3- to 7-membered carbon ring or heterocycle. A saturated cyclic structure is preferred, and a 3- or 4-membered ring is more preferred. As preferred cyclic structures, there can be mentioned a cyclopropane ring, cyclobutane ring, oxirane ring, oxetane ring, aziridine ring, azetidine ring, episulfide ring and thietane ring. Of these, a cyclopropane ring, cyclobutane ring, oxirane ring, oxetane ring and azetidine ring are preferred. A cyclopropane ring, cyclobutane ring and azetidine ring are more preferred. The cyclic structure may have a substituent.
Now, the reducing group will be described. Herein, the reducing group refers to an organic group. As representative reducing groups, there can be mentioned an amino group, alkylamino group (e.g., methylamino or diethylamino), arylamino group (e.g., phenylamino or diphenylamino), heterocyclic amino group (e.g., benzothiazolylamino or pyrrolylamino), alkylthio group (e.g., methylthio), arylthio group (e.g., 1-naphthylthio), heterocyclic thio group (e.g., 2-pyridylthio), aryloxy group (e.g., phenoxy), aryl group (e.g., phenyl, naphthyl or anthracenyl), aromatic or nonaromatic heterocyclic group (as the heterocycle, there can be mentioned, for example, a tetrahydroquinoline ring, tetrahydroisoquinoline ring, tetrahydroquinoxaline ring, tetrahydroquinazoline ring, indoline ring, indole ring, indazole ring, carbazole ring, phenoxazine ring, phenothiazine ring, benzothiazoline ring, pyrrole ring, imidazole ring, thiazoline ring, piperidine ring, pyrrolidine ring, morpholine ring, benzimidazole ring, benzimidazoline ring, benzoxazoline ring or 3,4-methylenedioxyphenyl ring), active methine group (which refers to a methine group substituted with two electron-withdrawing groups; herein, the electron-withdrawing groups refer to an acyl group, alkoxycarbonyl group, aryloxycarbonyl group, carbamoyl group, alkylsulfonyl group, arylsulfonyl group, sulfamoyl group, trifluoromethyl group, cyano group, nitro group and imino group; and these two electron-withdrawing groups may be bonded with each other to thereby form a circular structure) and a group containing a trivalent phosphorus atom (e.g., Ph2Pxe2x80x94 or (EtO)2Pxe2x80x94). These reducing groups may each have a substituent. It is preferred that the sum of nitrogen and carbon atoms thereof including those of the substituent be in the range of 1 to 50.
The compound of Type 4 is preferably represented by the general formula (E) or (F). 
With respect to RED41 and RED42 of the general formulae (E) and (F), not only the meanings but also the preferred ranges thereof are the same as those of RED12 of the general formula (B). Each of R40 to R44 and R45 to R49 represents a hydrogen atom or substituent. The substituent can be any of those which may be had by RED12. In the general formula (F), Z42 represents xe2x80x94CR420R421xe2x80x94, xe2x80x94NR423xe2x80x94 or xe2x80x94Oxe2x80x94. Each of R420 and R421 represents a hydrogen atom or substituent, and R423 represents a hydrogen atom, alkyl group, aryl group or heterocyclic group.
In the general formula (E), R40 preferably represents any of a hydrogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, heterocyclic group, alkoxy group, amino group, alkylamino group, arylamino group, heterocyclic amino group, alkoxycarbonyl group, acyl group, carbamoyl group, cyano group and sulfamoyl group. Of these, a hydrogen atom, alkyl group, aryl group, heterocyclic group, alkoxy group, alkoxycarbonyl group, acyl group and carbamoyl group are more preferred. A hydrogen atom, alkyl group, aryl group, heterocyclic group, alkoxycarbonyl group and carbamoyl group are most preferred.
With respect to R41 to R44, it is preferred that at least one thereof be a donating group. It is also preferred that R41 and R42; or R43 and R44 be simultaneously electron-withdrawing groups. More preferably, at least one of R41 to R44 is a donating group. Most preferably, at least one of R41 to R44 is a donating group while, among R41 to R44, nondonating group or groups are a hydrogen atom or alkyl group.
Herein, the donating group refers to a hydroxyl group, alkoxy group, aryloxy group, mercapto group, acylamino group, sulfonylamino group, active methine group, or group selected from preferred examples of the RED41 and RED42 groups. As the donating group, there can preferably be used any of an alkylamino group, arylamino group, heterocyclic amino group, 5-membered aromatic heterocyclic group having one nitrogen atom in its ring, which may be monocyclic or in the form of condensed rings, a nonaromatic nitrogen-containing heterocyclic group that is bonded to the carbon atom of the general formula (E) via its nitrogen atom and phenyl group substituted with at least one electron-donating group, wherein the donating group refers to a hydroxyl group, alkoxy group, aryloxy group, amino group, alkylamino group, arylamino group, heterocyclic amino group or nonaromatic nitrogen-containing heterocyclic group that is bonded to the carbon atom of the general formula (E) via its nitrogen atom). Of these, an alkylamino group, arylamino group, 5-membered aromatic heterocyclic group having one nitrogen atom in its ring, wherein the aromatic heterocycle refers to an indole ring, pyrrole ring or carbazole ring, and a phenyl group substituted with at least one electron-donating group, in particular, a phenyl group substituted with 3 or more alkoxy groups or a phenyl group substituted with a hydroxyl group, alkylamino group or arylamino group, are more preferred. An arylamino group, 5-membered aromatic heterocyclic group having one nitrogen atom in its ring, wherein the 5-membered aromatic heterocyclic group represents a 3-indolyl group, and a phenyl group substituted with at least one electron-donating group, in particular, a trialkoxyphenyl group or a phenyl group substituted with an alkylamino group or arylamino group, are most preferred. The electron-withdrawing groups are the same as those mentioned in the above description of active methine group.
In the general formula (F), the preferred range of R45 is the same as described above with respect to R40 of the general formula (E). Each of R46 to R49 preferably represents any of a hydrogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, heterocyclic group, hydroxyl group, alkoxy group, amino group, alkylamino group, arylamino group, heterocyclic amino group, mercapto group, arylthio group, alkylthio group, acylamino group and sulfonamino group. Of these, a hydrogen atom, alkyl group, aryl group, heterocyclic group, alkoxy group, alkylamino group, arylamino group and heterocyclic amino group are more preferred. Most preferably, each of R46 to R49 represents a hydrogen atom, alkyl group, aryl group, heterocyclic group, alkylamino group or arylamino group when Z42 represents a group of the formula xe2x80x94CR420R421xe2x80x94; represents a hydrogen atom, alkyl group, aryl group or heterocyclic group when Z42 represents a xe2x80x94NR423xe2x80x94; and represents a hydrogen atom, alkyl group, aryl group or heterocyclic group when Z42 represents xe2x80x94Oxe2x80x94.
Z42 preferably represents xe2x80x94CR420R421xe2x80x94 or xe2x80x94NR423xe2x80x94, and more preferably represents xe2x80x94NR423xe2x80x94. Each of R420 and R421 preferably represents any of a hydrogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, heterocyclic group, hydroxyl group, alkoxy group, amino group, mercapto group, acylamino group and sulfonamino group. Of these, a hydrogen atom, alkyl group, aryl group, heterocyclic group, alkoxy group and amino group are more preferred. R423 preferably represents a hydrogen atom, alkyl group, aryl group or aromatic heterocyclic group, and more preferably represents methyl, ethyl, isopropyl, t-butyl, t-amyl, benzyl, diphenylmethyl, allyl, phenyl, naphthyl, 2-pyridyl, 4-pyridyl or 2-thiazolyl.
When each of R40 to R49, R420, R421 and R423 represents a substituent, the total number of carbon atoms of each thereof is preferably 40 or less, more preferably 30 or less, and most preferably 15 or less. These substituents may be bonded with each other or bonded with other moieties (e.g., RED41, RED42 or Z42) of the molecule to thereby form rings.
It is preferred that the compounds of types 1, 3 and 4 according to the present invention be xe2x80x9ccompounds each having in its molecule an adsorptive group acting on silver halidesxe2x80x9d or xe2x80x9ccompounds each having in its molecule a partial structure of spectral sensitizing dye. More preferably, the compounds of types 1, 3 and 4 according to the present invention are xe2x80x9ccompounds each having in its molecule an adsorptive group acting on silver halidesxe2x80x9d. The compound of Type 2 is a xe2x80x9ccompound having in its molecule two or more adsorptive groups acting on silver halidesxe2x80x9d. The compounds of types 1 to 4 are more preferably xe2x80x9ccompounds having each a nitrogen-containing heterocyclic group substituted with two or more mercapto groups as an adsorptive groupxe2x80x9d.
With respect to the compounds of types 1 to 4 according to the present invention, the adsorptive group acting on silver halides refers to a group directly adsorbed onto silver halides or a group capable of promoting the adsorption onto silver halides. For example, the adsorptive group is a mercapto group (or a salt thereof), thione group (xe2x80x94C(xe2x95x90S)xe2x80x94), heterocyclic group containing at least one atom selected from a nitrogen atom, sulfur atom, selenium atom and tellurium atom, sulfido group, cationic group or ethynyl group. Provided however that, with respect to the compound of Type 2 according to the present invention, a sulfido group is not included in the adsorptive groups thereof.
The terminology xe2x80x9cmercapto group (or a salt thereof)xe2x80x9d as the adsorptive group means not only a mercapto group (or a salt thereof) per se but also, preferably, a heterocyclic, aryl or alkyl group substituted with at least one mercapto group (or salt thereof). Herein, the heterocyclic group refers to a 5- to 7-membered, monocyclic or condensed-ring, aromatic or nonaromatic heterocycle. As the heterocyclic group, there can be mentioned, for example, an imidazole ring group, thiazole ring group, oxazole ring group, benzimidazole ring group, benzothiazole ring group, benzoxazole ring group, triazole ring group, thiadiazole ring group, oxadiazole ring group, tetrazole ring group, purine ring group, pyridine ring group, quinoline ring group, isoquinoline ring group, pyrimidine ring group or triazine ring group. The heterocyclic group may be one containing a quaternary nitrogen atom, which may become a mesoion as a result of dissociation of a substituted mercapto group. This heterocyclic group can be, for example, any of an imidazolium ring group, pyrazolium ring group, thiazolium ring group, triazolium ring group, tetrazolium ring group, thiadiazolium ring group, pyridinium ring group, pyrimidinium ring group and triazinium ring group. Of these groups, a triazolium ring group (e.g., 1,2,4-triazolium-3-thiolate ring group) is preferred. The aryl group can be, for example, a phenyl group or naphthyl group. The alkyl group can be a linear, or branched, or cyclic alkyl group having 1 to 30 carbon atoms. When the mercapto group forms a salt, as the counter ion, there can be mentioned, for example, a cation of alkali metal, alkaline earth metal or heavy metal (e.g., Li+, Na+, K+, Mg2+, Ag+ or Zn2+), an ammonium ion, a heterocyclic group containing a quaternary nitrogen atom, or a phosphonium ion.
The mercapto group as the adsorptive group may further be tautomerized into a thione group. As such, there can be mentioned, for example, a thioamido group (herein a xe2x80x94C(xe2x95x90S)xe2x80x94NHxe2x80x94 group) or a group containing a partial structure of the thioamido group, namely, a linear or cyclic thioamido group, thioureido group, thiourethane group or dithiocarbamic acid ester group. As examples of suitable cyclic groups, there can be mentioned, for example, a thiazolidine-2-thione group, oxazolidine-2-thione group, 2-thiohydantoin group, rhodanine group, isorhodanine group, thiobarbituric acid group and 2-thioxo-oxazolidin-4-one group.
The thione groups as the adsorptive group include not only the above thione groups resulting from tautomerization of mercapto groups but also a linear or cyclic thioamido group, thioureido group, thiourethane group and dithiocarbamic acid ester group which cannot be tautomerized into mercapto groups, i.e., not having any hydrogen atom at the xcex1-position of thione group.
The heterocyclic group containing at least one atom selected from a nitrogen atom, sulfur atom, selenium atom and tellurium atom as the adsorptive group is a nitrogen-containing heterocyclic group having an xe2x80x94NHxe2x80x94 group capable of forming an iminosilver ( greater than NAg) as a partial structure of the heterocycle, or a heterocyclic group having an xe2x80x9cxe2x80x94Sxe2x80x94xe2x80x9d group or xe2x80x9cxe2x80x94Sexe2x80x94xe2x80x9d group or xe2x80x9cxe2x80x94Texe2x80x94xe2x80x9d group or xe2x80x9cxe2x95x90Nxe2x80x94xe2x80x9d group capable of coordinating to silver ion by coordinate bond as a partial structure of the heterocycle. The former heterocyclic group can be, for example, a benzotriazole group, triazole group, indazole group, pyrazole group, tetrazole group, benzimidazole group, imidazole group or purine group. The latter heterocyclic group can be, for example, a thiophene group, thiazole group, oxazole group, benzothiazole group, benzoxazole group, thiadiazole group, oxadiazole group, triazine group, selenoazole group, benzoselenoazole group, tellurazole group or benzotellurazole group. The former heterocyclic group is preferred.
As the sulfido group as the adsorptive group, there can be mentioned all the groups having a partial structure of xe2x80x9cxe2x80x94Sxe2x80x94xe2x80x9d. Preferably, the sulfido group is a group having a partial structure of alkyl (or alkylene) xe2x80x94S-alkyl (or alkylene), aryl (or arylene)xe2x80x94S-alkyl (or alkylene), or aryl (or arylene)xe2x80x94S-aryl(or arylene). This sulfido group may be in the form of a cyclic structure or xe2x80x94Sxe2x80x94Sxe2x80x94 group. As examples of sulfido groups forming a cyclic structure, there can be mentioned groups containing a thiolane ring, 1,3-dithiolane ring, 1,2-dithiolane ring, thiane ring, dithiane ring, tetrahydro-1,4-thiazine ring (thiomorpholine ring) or the like. Among the sulfido groups, groups having a partial structure of alkyl (or alkylene)xe2x80x94S-alkyl (or alkylene) are especially preferred.
The cationic group as the adsorptive group refers to a group containing a quaternary nitrogen atom. For example, it is a group containing an ammonio group or a nitrogen-containing heterocyclic group containing a quaternary nitrogen atom. However, the cationic group does not become part of an atomic group forming a dye structure (for example, cyanine chromophore). Herein, the ammonio group is, for example, a trialkylammonio group, dialkylarylammonio group or alkyldiarylammonio group. For example, as such, there can be mentioned benzyldimethylammonio group, trihexylammonio group or phenyldiethylammonio group. The nitrogen-containing heterocyclic group containing a quaternary nitrogen atom can be, for example, any of pyridinio group, quinolinio group, isoquinolinio group and imidazolio group. Of these, pyridinio group and imidazolio group are preferred. A pyridinio group is most preferred. The nitrogen-containing heterocyclic group containing a quaternary nitrogen atom may have an arbitrary substituent. However, when the nitrogen-containing heterocyclic group is a pyridinio group or imidazolio group, the substituent is preferably selected from, for example, an alkyl group, aryl group, acylamino group, chlorine atom, alkoxycarbonyl group and carbamoyl group. When the nitrogen-containing heterocyclic group is a pyridinio group, the substituent is most preferably a phenyl group.
The ethynyl group as the adsorptive group refers to a xe2x80x94Cxe2x89xa1CH group, whose hydrogen atom may be replaced by a substituent.
The above adsorptive groups may have an arbitrary substituent.
Furthermore, examples of suitable adsorptive groups include those listed on pages 4 to 7 of Jpn. Pat. Appln. KOKAI Publication No. (hereinafter referred to as JP-A-) 11-95355, (U.S. Pat. No. 6,054,260.
In the present invention, it is preferred that the adsorptive group be a nitrogen-containing heterocyclic group substituted with mercapto (e.g., a 2-mercaptothiadiazole group, 3-mercapto-1,2,4-triazole group, 5-mercaptotetrazole group, 2-mercapto-1,3,4-oxadiazole group, 2-mercaptobenzoxazole group, 2-mercaptobenzothiazole group or 1,5-dimethyl-1,2,4-triazolium-3-thiolate group), or a nitrogen-containing heterocyclic group having an xe2x80x94NHxe2x80x94 group capable of forming an iminosilver ( greater than NAg) as a partial structure of the heterocycle (e.g., a benzotriazole group, benzimidazole group or indazole group). More preferably, the adsorptive group is a 5-mercaptotetrazole group, 3-mercapto-1,2,4-triazole group or benzotriazole group. Most preferably, the adsorptive group is a 3-mercapto-1,2,4-triazole group or 5-mercaptotetrazole group.
Among the compounds of the present invention, those having, in the molecule thereof, two or more mercapto groups as a partial structure are also especially preferred. Herein, the mercapto group (xe2x80x94SH) may become a thione group when it can be tautomerized. Examples of such compounds may include a compound possessing in its molecule two or more adsorptive groups having the above mercapto group or thione group as a partial structure (e.g., a ring forming thioamido group, alkylmercapto group, arylmercapto group or heterocyclic mercapto group), and a compound possessing at least one adsorptive group having, in the adsorptive group per se, two or more mercapto groups or thione groups as a partial structure (e.g., a dimercapto-substituted nitrogen-containing heterocyclic group).
As examples of adsorptive groups having two or more mercapto groups as a partial structure (e.g., dimercapto-substituted nitrogen-containing heterocyclic groups), there can be mentioned a 2,4-dimercaptopyrimidine group, 2,4-dimercaptotriazine group, 3,5-dimercapto-1,2,4-triazole group, 2,5-dimercapto-1,3-thiazole group, 2,5-dimercapto-1,3-oxazole group, 2,7-dimercapto-5-methyl-s-triazolo(1,5-a)pyrimidine group, 2,6,8-trimercaptopurine group, 6,8-dimercaptopurine group, 3,5,7-trimercapto-s-triazolotriazine group, 4,6-dimercaptopyrazolopyrimidine group and 2,5-dimercaptoimidazole group. Of these, a 2,4-dimercaptopyrimidine group, 2,4-dimercaptotriazine group and 3,5-dimercapto-1,2,4-triazole group are especially preferred.
Although substitution with the adsorptive group may be effected at any position of the general formulae (A) to (F) and general formulae (1) to (3), it is preferred that the substitution be effected at RED11, RED12, RED2 and RED3 in the general formulae (A) to (D); at RED41, R41, RED42 and R46 to R48 in the general formulae (E) and (F); and at any arbitrary position except R1, R2, R11, R12, R31, L1, L21 and L31 in the general formulae (1) to (3). It is more preferred that, in all the general formulae (A) to (F), the substitution be effected at RED11 to RED42.
The partial structure of spectral sensitizing dye refers to a group containing a chromophore of spectral sensitizing dye, and refers to a residue resulting from removal of an arbitrary hydrogen atom or substituent from a spectral sensitizing dye compound. Although substitution with the partial structure of spectral sensitizing dye may be effected at any position of the general formulae (A) to (F) and general formulae (1) to (3), it is preferred that the substitution be effected at RED11, RED12, RED2 and RED3 in the general formulae (A) to (D); at RED41, R41, RED42 and R46 to R48 in the general formulae (E) and (F); and at any arbitrary position except R1, R2, R11, R12, R31, L1, L21 and L31 in the general formulae (1) to (3). It is more preferred that, in all the general formulae (A) to (F), the substitution be effected at RED11 to RED42. Preferred spectral sensitizing dyes are those typically employed in color sensitization techniques, which include, for example, cyanine dyes, composite cyanine dyes, merocyanine dyes, composite merocyanine dyes, homopolar cyanine dyes, styryl dyes and hemicyanine dyes. Representative spectral sensitizing dyes are disclosed in Research Disclosure, item 36544, September 1994. These spectral sensitizing dyes can be synthesized by persons skilled in the art to which the invention pertains in accordance with the procedure described in the above Research Disclosure or F. M. Hamer xe2x80x9cThe Cyanine Dyes and Related Compoundsxe2x80x9d, Interscience Publishers, New York, 1964. Further, all the dyes described on pages 7 to 14 of JP-A-11-95355 (U.S. Pat. No. 6,054,260) per se are applicable.
With respect to the compounds of types 1 to 4 according to the present invention, the total number of carbon atoms is preferably in the range of 10 to 60, more preferably 10 to 50, most preferably 11 to 40, and optimally 12 to 30.
With respect to the compounds of types 1 to 4 according to the present invention, a one-electron oxidation thereof is induced upon exposure of the silver halide photographic lightsensitive material wherein use is made of the compounds, followed by reaction. Thereafter, another electron, or two or more electrons depending on the type of compound are released to thereby cause further oxidation. The oxidation potential with respect to the first electron is preferably about 1.4 V or below, more preferably 1.0 V or below. This oxidation potential is preferably higher than 0 V, more preferably higher than 0.3 V. Thus, the oxidation potential is preferably in the range of about 0 to about 1.4 V, more preferably about 0.3 to about 1.0 V.
Herein, the oxidation potential can be measured in accordance with the cyclic voltametry technique. For example, a sample compound is dissolved in a solution consisting of a 80%:20% (vol. %) mixture of acetonitrile and water (containing 0.1 M lithium perchlorate), and nitrogen gas is passed through the solution for 10 min. Thereafter, the oxidation potential is measured at 25xc2x0 C. and at a potential scanning rate of 0.1 V/sec with the use of a glassy carbon disk as a working electrode, a platinum wire as a counter electrode and a calomel electrode (SCE) as a reference electrode. The oxidation potential vs. SCE is determined at the peak potential of cyclic voltametry wave.
With respect to, among the compounds of types 1 to 4 according to the present invention, those which undergo a one-electron oxidation and, after a subsequent reaction, further release another electron, the oxidation potential at the latter stage is preferably in the range of xe2x88x920.5 to xe2x88x922 V, more preferably xe2x88x920.7 to xe2x88x922 V, and most preferably xe2x88x920.9 to xe2x88x921.6 V.
On the other hand, with respect to, among the compounds of types 1 to 4 according to the present invention, those which undergo a one-electron oxidation and, after a subsequent reaction, further release two or more electrons to thereby effect oxidation, the oxidation potential at the latter stage is not particularly limited. The reason is that the oxidation potential with respect to the second electron cannot be clearly distinguished from the oxidation potential with respect to the third electron et seqq., so that it is often difficult to practically accomplish accurate measuring and distinguishing thereof.